Such a communication switching system is already known in the art, e.g. from the European patent application No. 8890007.1 (M. DE PRYCKER 2--2) which generally corresponds to commonly assigned U.S. Pat. No. 5,020,052 which issued on May 28, 1991 under the title "Packet Switching Network". Therein a stream of cells of information belonging to a same communication is transmitted over a same virtual communication path established at the start of the communication by means of a path setup cell.
To assess the transmission quality of such a communication it would be possible to number all the cells thereof but this would require too much bandwidth due to cell length increase. Instead, it would also be possible to insert numbered test cells in the stream, each test cell being provided for a predetermined number of cells and to assess the transmission quality by verifying if all the test cells are received at the output. Such a solution has the advantage of using only a limited amount of additional bandwidth but it only permits to verify that due to transmission errors test cells are lost and not that other cells are lost or that cells are added to the communication. So the accuracy of the arrangement is relatively small.